Low field magnetotransport in La0.7Sr0.3MnO3 films

Abstract
We have observed a strong correlation between the degree of epitaxy and the low field resistance versus field R(H) behavior in highly textured La0.7Sr0.3MnO3 films grown by pulsed laser deposition on SrTiO3 substrates. Highly epitaxial films show a small temperature dependent low field hysteretic R(H) peak near the magnetic ordering temperature (Tc), when the applied field is parallel to the transport current (J∥H). In contrast, films with reduced epitaxy show a much larger low field hysteretic R(H) behavior with a pronounced in-plane angular dependence. The magnitude of this response grows with decreasing temperature below Tc. Our data and analysis suggest that even low angle grain boundaries play a fundamental role in transport properties in colossal magnetoresistive materials.